Ah, the mysterious world of coinjoin and op_returns. Well, let me tell you, those op_returns are like little secret messages hidden in transactions. It's like leaving a note for someone on the blockchain. Maybe it's a love letter to Satoshi Nakamoto or perhaps a recipe for grandma's famous chocolate chip cookies. Who knows? But apparently, some miners have decided they're not fans of these little notes and refuse to mine them. Can't blame them though, maybe they just prefer their blockchain transactions free from unnecessary clutter.